A prior art radial shaft sealing ring is disclosed in DE-AS 23 39 353. The backside of the sealing element of this prior art sealing ring has freely protruding fiber ends which are oriented in the direction of the sealed-off medium. In the region of the contact area, the fiber ends lie against the sealed-off shaft and are deflected sideways under the influence of friction if there is a rotary movement, whereby a dynamic return effect aiding the sealing action is exerted on the sealed-off medium penetrating into the sealed zone. If the shaft is standing still, this effect ceases and undesirable leakage can be the result.
The effectiveness of this prior art seal is further greatly influenced by the fact that the fiber ends, in addition to high mobility, have a certain amount of elasticity. Both properties depend greatly on the available cross section and they are impaired when a reduction in cross section occurs due to wear. Thus, these prior art radial shaft sealing rings have a disadvantageous steadily decreasing dynamic sealing effect during their useful life.